lifted club cars - lifted ezgo
Home FAQDonate Who's Online
Go Back   Buggies Gone Wild Golf Cart Forum > Golf Cart Repair and Troubleshooting > Gas EZGO
Gas EZGO Gas EZGO Marathon, Medalist, TXT and RXV.



Post New Thread  Reply
 
Thread Tools Display Modes
Old 02-24-2012, 03:47 PM   #1
seahunter
Not Yet Wild
 
Join Date: Nov 2009
Posts: 28
Default 90 Marathon 2 Stroke no power in bottom end

This thing is starting to drive me crazy. I've tried just about everything I can think off. I must be missing something obvious.

Symptoms:
Slow, no power on the bottom of the rpm range. Once it gains RPM it runs pretty well until the RPM drops back in the lower ranges again.

You will be running along and out of the blue you will get a couple of dead misses then it will run OK again.

Existing Conditions:
Compression 95 PSI. Adding oil to the cylinder does not increase the compression.

It starts on the turn of the key, even in very cold conditions

New seals installed last Spring

Almost acts like the timing is retarded. Checked, in the middle of the adjustment slot

Has HEI ignition upgrade on it.

New carb and the plugís insulator is a nice light brown color.

Motor sounds good while running. No pre-ignition, bangs or rattle

Pulsar fails ohm tests. Still outputs Ĺ volt when cranked

A new spark plug seems to help the miss for a while. No real affect on the no power in the lower RPM issue

Removing muffler has no affect
seahunter is offline   Reply With Quote
Alt Today
BGW

Golf car forum Sponsored Links

__________________
This advertising will not be shown in this way to registered members.
Register your free account today and become a member on Buggies Gone Wild Golf Cart Forum
   
Old 02-24-2012, 05:08 PM   #2
hms11
Not Yet Wild
E-Z-GO
 
Join Date: Dec 2011
Location: Ontario, Canada
Posts: 19
Default Re: 90 Marathon 2 Stroke no power in bottom end

95psi is about 35-45 psi short of what you need. Believe it or not these little sewing machines need 130-140psi comp to run correctly.

Actually, judging by most of the comments you see on here, your lucky the thing runs at all being below 100.

Sounds like a rebuild is in store for your little 3pg, luckily their cheap kits, especially if you only end up needing a top end rebuild.
hms11 is offline   Reply With Quote
Old 03-02-2012, 03:38 PM   #3
seahunter
Not Yet Wild
 
Join Date: Nov 2009
Posts: 28
Default Re: 90 Marathon 2 Stroke no power in bottom end

The compression maybe on the lower side, at least when measured with this compression gauge, but I donít see that as being the root cause of the problem. The fact that a "wet" compression test yielded the same results as a "dry" compression test pretty much tells me it is not a ring problem.

How would low compression cause an intermittent miss?
seahunter is offline   Reply With Quote
Old 03-02-2012, 03:59 PM   #4
hms11
Not Yet Wild
E-Z-GO
 
Join Date: Dec 2011
Location: Ontario, Canada
Posts: 19
Default Re: 90 Marathon 2 Stroke no power in bottom end

Well the intermittent miss could be a whole different ball of wax, but the fact is that 95psi is just not gonna cut it. Low compression is definately going to kill your power, especially in the bottom end when the cart really needs the power to get moving. Like I said earlier... I'm actually amazed the thing runs at all with below 100psi, let alone runs decent once it starts winding out.

If Dave or any of the other Marathon 2-stroke experts come along I'm sure they'll agree. Before you spend to much time hunting down other problems your going to have to fix the compression problem.

Since the plug seems to be nice and golden brown I'm going to go ahead and say I doubt its a fuel or spark issue.

Last edited by hms11; 03-02-2012 at 04:03 PM.. Reason: Added the bit at the end.
hms11 is offline   Reply With Quote
Old 03-02-2012, 04:07 PM   #5
Dave Box
Respect the Cart
 
Dave Box's Avatar
E-Z-GO
 
Join Date: May 2010
Location: Rocky Mount, Virginia
Posts: 2,189
Default Re: 90 Marathon 2 Stroke no power in bottom end

hms11 is on the money. Your engine is not going to be that great with that compression. The wet compression is not a valid test on a horizontal cylinder as the oil is not going to be able to seal the rings as it does on a vertical cylinder.
As you will be aware the 2 stroke engine needs to produce crankcase pressure oscillations in order to drive the fuel pump and transfer fuel from the crankcase to the cylinder. If there is sufficient blow by you may well be interfering with the rhythm of the oscillations causing a momentary lapse in fuel delivery.
If everything else checks out (including the driven clutch not being jammed open) then I too see a top end rebuild in your future.

Dave
Dave Box is offline   Reply With Quote
Old 03-03-2012, 09:22 AM   #6
seahunter
Not Yet Wild
 
Join Date: Nov 2009
Posts: 28
Default Re: 90 Marathon 2 Stroke no power in bottom end

I think I found the problem. The cylinder is mounted incorrectly. It's supposed to be mounted horizontally, not vertically as it is now.

Guys, I'm pretty sure it’s not a compression issue. I have enough experiance on two strokes to know a compression issue when I see one. Yes, the compression might be a bit low but it’s not the root cause of this problem.

How does the ignition advance work on these things? I like the clutch idea as well. That could explain the perceived loss of power
seahunter is offline   Reply With Quote
Old 03-03-2012, 09:35 AM   #7
simple man
Gone Wild
 
simple man's Avatar
E-Z-GO
 
Join Date: Aug 2011
Location: Bunnell, Florida
Posts: 2,408
Default Re: 90 Marathon 2 Stroke no power in bottom end

Just a thought, I'd try another compression gauge. I say this because, as others have said, the engine shouldn't even run with the reading you obtained!
simple man is offline   Reply With Quote
Old 03-03-2012, 10:21 AM   #8
hms11
Not Yet Wild
E-Z-GO
 
Join Date: Dec 2011
Location: Ontario, Canada
Posts: 19
Default Re: 90 Marathon 2 Stroke no power in bottom end

There is no advance mechanism, mechanical or electrical. The timing is set at 2degrees (ish) BTDC and doesn't move. Its part of the reason that this motor makes 11HP and the same motor in a polaris 4-wheeler makes 20HP, it has an advance curve which I'm 90% sure is built into the flywheel somehow.
If your sure the compression isn't the problem (which I don't understand. Again, these engine NEED 130psi+) then I'm not sure what else to tell you. Like Dave and I and others have said, there's no point in even looking anywhere else until that compression number is 40 psi higher. All your doing is tuning up a sinking ship, and no matter how much you polish it, its still going to be a turd.

Like Simple Man said, try another compression gauge, if it still comes up 95psi then no matter how much you replace otherwise, its not getting better without a top end rebuild. And remember, just because a wet test doesn't change the reading, doesn't mean you haven't melted a piston, no amount of oil will fix that.
hms11 is offline   Reply With Quote
Reply
Go Back   Buggies Gone Wild Golf Cart Forum > Golf Cart Repair and Troubleshooting > Gas EZGO


Thread Tools
Display Modes


Similar Threads
Thread Forum
EZ Go 2 stroke gas has NO power Gas EZGO
93 marathon 4 stroke no power and smoke Gas EZGO
89 EZ-GO 2 stroke has no power Gas EZGO
1987 marathon bottom end tore up Gas EZGO
87 - 2 stroke Loss of power when hot Gas EZGO


All times are GMT -5. The time now is 10:28 PM.


Club Car Electric | EZGO Electric | Lifted Golf Carts | Gas EZGO | Used Golf Carts and Parts

Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
This Website and forum is the property of Buggiesgonewild.com. No material may be taken or duplicated in part or full without prior written consent of the owners of buggiesgonewild.com. © 2006-2017 Buggiesgonewild.com. All rights reserved.